import numpy as np
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from pandas import DataFrame
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import pandas._testing as tm
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def test_head_tail_generic(index, frame_or_series):
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# GH#5370
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ndim = 2 if frame_or_series is DataFrame else 1
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shape = (len(index),) * ndim
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vals = np.random.randn(*shape)
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obj = frame_or_series(vals, index=index)
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tm.assert_equal(obj.head(), obj.iloc[:5])
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tm.assert_equal(obj.tail(), obj.iloc[-5:])
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# 0-len
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tm.assert_equal(obj.head(0), obj.iloc[0:0])
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tm.assert_equal(obj.tail(0), obj.iloc[0:0])
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# bounded
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tm.assert_equal(obj.head(len(obj) + 1), obj)
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tm.assert_equal(obj.tail(len(obj) + 1), obj)
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# neg index
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tm.assert_equal(obj.head(-3), obj.head(len(index) - 3))
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tm.assert_equal(obj.tail(-3), obj.tail(len(index) - 3))
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def test_head_tail(float_frame):
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tm.assert_frame_equal(float_frame.head(), float_frame[:5])
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tm.assert_frame_equal(float_frame.tail(), float_frame[-5:])
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tm.assert_frame_equal(float_frame.head(0), float_frame[0:0])
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tm.assert_frame_equal(float_frame.tail(0), float_frame[0:0])
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tm.assert_frame_equal(float_frame.head(-1), float_frame[:-1])
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tm.assert_frame_equal(float_frame.tail(-1), float_frame[1:])
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tm.assert_frame_equal(float_frame.head(1), float_frame[:1])
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tm.assert_frame_equal(float_frame.tail(1), float_frame[-1:])
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# with a float index
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df = float_frame.copy()
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df.index = np.arange(len(float_frame)) + 0.1
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tm.assert_frame_equal(df.head(), df.iloc[:5])
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tm.assert_frame_equal(df.tail(), df.iloc[-5:])
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tm.assert_frame_equal(df.head(0), df[0:0])
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tm.assert_frame_equal(df.tail(0), df[0:0])
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tm.assert_frame_equal(df.head(-1), df.iloc[:-1])
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tm.assert_frame_equal(df.tail(-1), df.iloc[1:])
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def test_head_tail_empty():
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# test empty dataframe
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empty_df = DataFrame()
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tm.assert_frame_equal(empty_df.tail(), empty_df)
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tm.assert_frame_equal(empty_df.head(), empty_df)
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